This doctoral thesis bridges experimental research and policy issues in the marine environment. The focus is on the challenging relation between nature conservation and current fisheries practices. The study sites investigated consist largely of sedimentary sand banks and swales, situated in North-Western Europe. A particular biogenic habitat has been chosen to study both the ecological importance and the resilience towards the physical disturbance of beam-trawling. This habitat is Lanice conchilega reefs, which are distinct aggregations of tube dwelling polychaetes (bristle worms). The implications of these tube worm reefs for the benthic environment as well as for flatfish species are studied in depth and several experiments (in lab and field conditions) quantify the impact of beam trawl fisheries. The thesis finishes by integrating these results in legal policy options and discusses the process of MPA-implementation. The general discussion elaborates how this thesis may contribute to the application of an ecosystem approach to support marine management